Power distribution units are used to distribute power supplied by a main electrical source to a variety of devices requiring power. The power distribution unit may include an internal power bus that powers one or more circuits. Each of these circuits may include a protective device, such as a fuse or a circuit breaker, which is accessible through one of the walls or panels of the unit. A power distribution unit may have the capacity for more circuits than are required when the unit is installed, which provides for future expansion. In such installations, one or more of the circuits may be left open, that is, without having any protective device.
The openings through which these omitted protective devices will extend are often covered to prevent unwanted or accidental contact with the power bus within the unit. This may be done with a flat plate or blank cover secured over the opening. When a protective device is inserted into the opening to provide an additional power circuit, this blank is then removed and discarded. A mounting plate may then be attached to the protective device and the device inserted into the power distribution unit. When a switched circuit breaker is the protective device installed, the mounting plate may incorporate a finger guard structure to protect the switch from accidental contact opening the circuit and interrupting power in the circuit.
Several concerns arise in the area of finger guards, including ease of use and reliability. Providing separate mounting plates and blank covers can be difficult to coordinate and manage, especially when the circuit protective devices are added later. Further developments in finger guards are desired.